Aspects and embodiments of the invention are directed to the field of optical wavefront sensing; more particularly to an optical wavefront sensing apparatus and associated method; and most particularly to a wavefront sensing technique using Polarization Rotation INTerferometry (PRINT), associated apparatus, and applications thereof.
Current approaches for measuring the phase of an optical wavefront include, without limitation, Shack-Hartmann interferometry, point diffraction interferometry, shear interferometry, and phase retrieval. Table 1 below lists some comparative attributes of these approaches and what might be considered ideal.
TABLE 1Affected byPhaseamplitudeResolutioninformationinformation?SpeedShack-HartmannLowIndirectWeaklyNeed(gradient)processingPoint DiffractionHighw/ ambiguityYesReal-timeShearLowIndirectModestlyNeed(gradient)processingPhase RetrievalHighDirectYesNeed heavyprocessingIdealHighDirectNoReal-time
As evident from Table 1, none of the listed approaches provides the ideal combination of self-referencing, real-time, direct, high resolution phase measurement unaffected by signal amplitude. Phase shifting interferometry has also proved to be an effective way to measure the phase profile; but most of these methods typically require either a time-sequence of measurements or a separate reference field.
The inventors have thus recognized the advantages and benefits to be provided by methods and apparatus that address and overcome the aforementioned shortcomings and challenges in the art, especially in applications including, but not limited to, astronomical observation, biomedical imaging, and free-space communication, etc.